If Dirk's not making his shots, he's not doing much of anything else...same with Jason Terry, Stackhouse, and Devin Harris. Only guys who are still effective are Howard and Bass!
Whereas for the Spurs, if Duncan, Parker, or Ginobili have an off night offensively, they are still able to affect the game in other areas. Dallas needs more players like that in order to get over their mental deficiencies. They tend to give up in all other areas of the game if their shots aren't falling. You saw that against GS last season and this season as well. They need more all around players, not one dimensional ones. And it doesn't help that they have no real leader and that Avery keeps changing their lineups and his "team philosophy"